Refining of rosin and rosin derivatives



Patented July 27, 1943 REFINING OF ROSIN AND ROSIN DERIVATIVES Donald A.- Li-ster Brunswickp Gan, -a s signor to Hercules Powder. Company, Wilmington, Del., 2.

. corporation ofDelawaie No Drawing. Application January 9; 1941,

zSerialNo.373,803

7 Claims. (91. 2605111) This invention relatesto the refining of rosin and rosin derivatives and more particularly to the treatment of impure or dark-colored rosin with i urfural. Rosin has been heretofore refined by forming a'solution thereof in a light petroleum distillate-followed by selective solvent extraction "of the solution with 'furfural which exer-ts'a selective solvent action upon the rosin color bodies. Following this extraction step, the solutionof refinedrosin was evaporated to remove the petroleum distillate and leave a residue of refined resin. The extract was also evaporated to remove the furiural and leave a residue of dark rosin. An example-of such a rosin refining procedure is-that described in the Kaiser and Hancock Patent No. 1,715,085 wherein the light petroleum distillate usedis gasoline. In the procedure described'in that patent; the mixture of f-urfurai, gasoline, and rosinseparatesinto'two'phases; one phase rich in furfural but containing some dissolved-gasoline and also containing the rosin col-or bodies; the other phaseri'ch in gasoline but containing some dissolved furiural and containing the "pale rosin. A. major dimculty connected with this priorrosin refining process is that the selective action of the system is diminished by solution of furfural in the gasoline phase and of gasoline in the furfural phase, each phase reaching saturation with respect to the chief ingredient of the other phase. The result is a reduced efficiency with which dark-colored and undesirable ingredients of the rosin are separated .from'light colored ingredients, since the solubility of the solvents in each other diminishes the dissimilarity of the phases.

and undesirable ingredients being appreciably soluble in the gasoline phase. 3

.An object of the present invention is to' devise a" process whereby rosin of a given' 'col'or grade can be obtained more economically and more effio'ientiy'or whereby rosin of a paler color grade may be, produced. Another object is to provide a process for refining rosin which-gives'an improved yield of product. Other objects will more fully hereinafter appear.

I have discovered :that :by. thaintroduction to the mixture of :fiu'fural', light petroleum distillate to the extent of more than 17% "by .weightxbased on: the: weight "of-the furfura'l-and "Water, the furfural and light petroleum distillate dissolve to 'a-il'esser cxtentin on another 'soathat either a, paler gradefof ll'fifillfid' rosin or L a higher yield Accordingly, the efficiency of the separation is likewise diminished, the dark-colored of rosin of a given color, or a hi her yield-of a paler grade may be obtained. Preferably; this is accomplished by dissolving water'in the furfural to be employed, to the extent of more'than 1% by weight-based on the weight of furfural and Water. However though less preferably, water. may be added to the mixture of anhydrous or substantially =anhydrous furfural, gasoline, and rosin,whereupon"water will dissolve in the iurfural phaseincreasirig the selective distribu tion of the rosin ingredients between the two phases. The amountoi water may rangeup to the saturationpoint of thefur fural' at ordinary atmospheric temperatures '(15 to "25 C.). "If desired; an excess of water maybe present, altho-ugh'such excessforms a third phase and has noeiiectin'the process other than to maintain the furfural saturated with Water. In general, the" presence of .a't'hird phase of water is undesirable because of mechanical diificulties introducedinoonnection with :the' separation of the phases irom'one another.

"The light petroleum distillate employed in the process of: the? resent invention may be any light mobile petroleum distillate capable of yielding a rosinLsoI-ution of high concentration but of low viscosity. In general; any petroleum distil late'having-a boiling point range not above that of kerosene may he utilized. For example, Im'ay use petroleum ether (boiling range 40-60 Ci), petroleum spirit (boiling range -430": 6.),

V. M. 8; P; naphtha '(boiling range -160" C.)',

mineral spirit (90% below 209C); gasoline sueh as that suitable for use in 'spark' fired internal combustion motors (having an initial boiling point of from about 21: C. up to about 66 C. and an end boiling point'of from about 177C. to about 232 (3.). I may use gasoline having a higher initial boiling point such for example, an initial boiling point of 93 C., which is unsuitable. for-useas motor fuel, but which is termedgasoline in the industry. I may use Stoddard solvent (50% or more below 177 0.,

end point not higher than 210 0.), or I may use kerosene which has aboiling range of -.270 C. I may .likewise use any of the foregoing "light petroleum distillates which has been treated with furfural, sulfur dioxide, sulfuric acid, chlorosu-lfonic acid,, selective adsorbents such as clay, etc. for removal of nonparaffin constituents. It is preferred, however, to use light petroleum distillate of the typecommercially referred to in the industry as gasoline. In general; it is preferred to use light petroleum distillate *boiling not" above 200C preferably parafrlnic in character and having a critical solution temperature in aniline not lower than 60 C.

The process of the present invention is particularly suitable for refining rosin containing visible or latent color bodies, for example, wood or gum rosin. Instead of rosin, equivalent materials suchas the rosin acids such as commercial abietic acid, pimaric acid, sapinic acid, etc. may be treated. The invention is also suitable for refining rosin derivatives such as modified rosins such as rosin which has been treated with a hydrogenating catalyst in the absence of hydrogen and known as Hyex rosin, hydrogenated rosin, polymerized rosin, isomerized rosin, heat treated rosin, etc., rosin esters such as ester gum, esters of rosin with methanol, ethanol,

propanol, butanol, amyl alcohol, cetyl alcohol, lauryl alcohol, stearyl alcohol, furfuryl alcohol, abietanol, phenol, benzyl alcohol, etc. or with polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, erythritol, pentaerythritol, sorbitol, mannitol, etc., Where such rosin derivatives contain visible or latent color bodies. The invention is also applicable to esters of modified rosins'such as esters of Hyex rosin, hydrogenated rosin, polymerized rosin, etc. Similarly, the invention is suitable for the refining ,of rosin alcohols and hydrogenated rosin alcohols such as are obtained by reducing the rosin acid carboxyl group to a hydroxyl (e. g. abietic acid to abietanol), etc., and organic esters of such rosin alcohols, and other rosin derivatives of like nature where such derivatives contain visible or latent color bodies.

The process of the present invention comp-rises commingling light petroleum distillate such as gasoline, rosin or the like, furfural, and water in any manner which will result in the formation of separable phases; the one, phase rich in furfural and containing dissolved therein the rosin being rich in gasoline and containing a small amount of dissolved furfural, light colored rosin or the like, and only a trace of dissolved'water. Excess water, if present in slight excess so as to form; a third separate phase, does not affect the refining process.

It is preferred to dissolve the rosin or the like in the light petroleum distillate such as gasoline to the extent of from about to about 40% of rosin by weight based on the weight of rosin and gasoline. A convenient concentration is 20% by weight. The amount of furfural may range from about 50% to about 150% by weight based on the weight of rosin taken, depending upon the extent of coloration of the rosin, and numerous other factors. A preferred procedure is to maintain the mixture at an elevated temperature sufficient to render it homogeneous, followed by cooling the mixture to '25" F. or below, separation of the furfural phase from the' EXAM PLE 1 A solution comprising 850 parts by weight of gasoline and 150 parts by weight of dark-colored rosin was passed upwardly through a packed tower, a solution comprising 106 parts by weight of anhydrous furfural and 4 parts by weight of water being passed downwardly through the tower in a countercurrent relationship. The furfural phase dissolved from the gasoline phase a portion of the rosin very dark in color. The furfural phase was discharged at the bottom, the furfural and water evaporated and recycled, the gasoline layer containing a portion of the original rosin which was very light in color was discharged at the top of the tower and evaporated, the recovered gasoline being recycled.

" An identical run wherein 106.8 parts by weight glycerol, 1

of technical furfural containing 0.75% of water was employed instead of the mixture of 106 parts of anhydrous furfural and 4 parts of water, gave a materially darker refined rosin in a lower yield. A further run wherein 106 parts by weight of anhydrous furfural was employed instead of furfural containing water gav a still lower yield of a still darker refined rosin.

EXAMPLE 2 Three hundred grams of solution comprising 50g. of FF wood rosin in 250 g. of gasoline was placed in a separatory funnel and 45 g. anhydrous iurfural and l g. water were added, the mixture shaken vigorously and allowed to stand whereupon a 26 g. dark layer was separated off. The residual gasoline layer was treated again with 23 g. anhydrous furfural and 1 g. water, whereupon a 36 g. dark layer was separated ofi. The gasoline layer remaining was evaporated and a 79% yield of rosin grading I in color was recovered.

Further evidence of the effect of dissolved water in the furfural employed upon the color grade and yield of purified rosin is indicated in the following table of runs, in each of which 300 g. of a solution of 50 g. of FFwood rosin in gasoline was contacted with the indicated amount of anhydrous furfural containing the indicated amount of water, the residual gasoline phase being separated and again washed with anhydrous furfural containing water as indicated under .se'cond wash."

Table 1 Example No.

3 (blank) 4 5 0 First Wash:

Anhydrous furfural cubic centimetcn. 40 40 30 30 Water 0..-. None 1.0 1.0 1.0 Wt. of water (based on wt. of furfural and water) 0.0 2.1 2.8 2.8 Volume of furfural layer separating cubic centimeter.. 8. 5 23.0 10. 2 10. 5 Second wash:

Anhydrous furfural cubic centimeter 20 20 20 14 Water do None 1.0 1.0 0.7 Wt. of Water 0.0 4.1 4.1 4.1 Volume of furiural layer separating cubic centimeter 29. 7 32.0 29. 6 18. 0 Results-refined rosin- Yield .pcr cent. 80.8 78. 5 85. 2 87.6

Lovibond color, Am-

ber+Red 80+8.5 80+1.0 80+3. 7 80+6.0 Rosin color grade G I H G Examples 3 and 4 show that where equal quantities of furfural are used, the addition of water resultsin a considerably paler rosin, namely a rosin of 7.5 less red and two color grade higher. The slightly lower yield is explained by considerin the volumes of dark furfural layer separating off in the first wash. In the presence of 2.1% of water less furfural dissolved in the gasoline yield and improved color.

set forth above in detail.

layenand so there was a larger furfural layer present in whichthe rosin color bodies could dissolve. By extracting this separated iurfural phase with fresh gasoline, itwas found that a considerable amount of pale rosin could be recovered therefrom.

In Example 5, the volume of furfural-water purified rosin of a color of 2.5 red lower than the purified rosin of the blank. The procedure of this example therefore resulted in both higher The anhydrous furfural employed inthe foregoing examples was prepared from technical furfural containing 0.75% water by first vacuum distilling, and then'heating in a 100-105 0. oil bath at 50-60 mm. absolute pressure with carbon dioxide bubbling up through the furfural until the distillate contained no moisture.

I have still'further discovered that'improved results may be obtained by using furfural containing more than 1% by weight of water in the preparation of a substantially petroleumhydrocarbon insoluble resin from the total resinous extract from pine wood obtained with an aromatic hydrocarbon such as benzene. For example I may dissolve such a total resinous extract (left upon evaporation of the benzene) in a light petroleum hydrocarbon such as gasoline at an elevated temperature, add with stirring furfural containing more than 1% of water in an amount equal to say one-third of the weight of the crude resin taken, to cause dissolution of that 'portionof the resinous extract which is substantially insoluble in light petroleum hydrocarbons at room temperature, and effect separation of-thefurfural phase, leaving a gasoline solution of impure rosin (FF grade) as the rai'finate. I may' then advantageously extract the impure rosin solution or raffinat'e with fresh furfural containing more than 1% of water in the manner Inthis way, I effect a better separation of the petroleum-insoluble resin prior'to the refining of the crude rosin.

In the procedure just described I may agitate the crude total resinous extract with a mixture of the gasoline and the furfuralcontaining more than 1% of water, instead of first dissolving the extract in gasoline; Likewise, I may effect the inter-mixture and commingling of the crude total extract, the gasoline, and the furfural containing more than 1% of water, at an elevated temperature which may or may not be sufliciently high to bring about miscibility, followed by cooling t separate the phases. I a

Following are examples'showing the combined procedure just described;

EXAMPLE 7 The total benzene extract of pine wood (known as FF No. 3 rosinand comprising a mixture of FF wood resin and the petroleum hydrocarban-insoluble resin) had the following analysis Gasoline-insoluble 16.3

. first 20% for use.

mained in suspension. The solution was diluted withl g. of additional narrow range gasoline of suitable temperature to g'ive'325 g. of solution 5 To this solution'ther was added with rapid stirring a solution consisting of 25 g. of anhydrous furural and 0.5 g.of water. The addition of this caused solution of the more insoluble portion of .thejgasoline-insoluble' constituents of the crude resin by forming a lower furfural layer containing those constituents. The mixture was maintained at about F. during this step. I The upper gasoline layer of partially refined rosin (FF) v at 90 F. was then decanted c- To this gasoline layer of FF rosin there was added 60 g. of anhydrous furfural in admixture .with 1.2 g. of water (dissolved therein), with agitation at about 85 F. for 5 minutes. The mixture was then allowed to settle whereupon the lower furfural layer of impurities and color bodies was drawn off. The refined rosin solution (the upper layer) was evaporated to rec-over the refined rosin. There was obtained a. yield of 47.8

g. of refined rosin having a color .of H7 on the photoelectric scale based on the U. S. Government rosin standard. This was a yield of- 63.7%

of the original crude extract. H

EXAMPLES 8 r0 10 Example 7 was duplicated exactlyv except that the amount of water based on the weight of fur- 'fural and water was progressively increased and the amount of furfural and water used for refining the gasoline' layer left after the first extraction was progressivelydiminished so as to v give the same color of refined rosin. In this way direct comparison of the yields of refined rosinof a given color grade was possible. The conditionsand results are set/forthin the following :Table II wherein there have also been tabulated Example 7 and a comparative run using no water (the top run in TableII) Q '7 I Table'II Ratio of anhydrous urural to origsg g g fi g inal crude rcsin- Refined msm 'Example on weight ous extract of f urfural anc. water In first Insecond extraction extraction Yield Color Blank compar- Per can! I Per cent I atlve run ....I 0.0 33% 133% 59.2 H1 L96 33%! 79% 617 H1 ..3 2.9 23s! 66% 65.0 H1 3.84; 33f 47.9 65. 5 f17 4.75 33%; 47.0 57.3 H1

Solution of the Water in the furfural in this run Was obtained by hating the inlxturoof furfural and water to about C. During the second extraction some of this water was thrown out as droplets in the furfural layer. 1

The anhydrousfurfural used in the runs'tabw lated in the foregoing Table II was prepared by distilling'fresh technical furfural rejecting the over and retaining the next 60% over Examination of the foregoing Table II shows a .marked advantage of the present invention in water, the better the results.

color grade is produced. The table further illustratesthat thereisbut little. improvement in *furfural used in the refining of the impure rosin (i. e. the second extraction) was progressively reduced so as tojgive a rosin of color H7, thereby enabling the yields to bedirectly compared. The

next color division above H is: I.

The amount of water dissolved in the furiural may vary upwardly from 1% by weight of the f urfural and water to saturation at atmospheric temperature. Preferably, at least about 2% ,of water is employed The higher the amountof saturated at the temperature at which phase separation'is efiected with water is. particularly 5' advantageous and convenient. Furfural will dissolve water to a 4.8%"solution at C.

From the foregoing, it will be seen that the process of the present invention gives rise to numerous advantages over the prior art process of refining rosin'with 'furfural, among theseadvantages being the improved yield of light-colored rosin which is obtainable with the process of the invention. Numerous other advantages of the process will be apparent to those skilled "in the art.

It will be understood that the details and a;

"amples hereinbefore set forth are illustrative only and that the invention as broadly described and claimed is in no way limited thereby.

What Iclaim and desire to protect by Letters Patent is:

1. The method of refining a'rosinyl material selected from the group consisting of rosins,

rosinvacids, rosinesters, rosin alcohols, and esters of rosin alcohols which comprisestreating a solu tion of said material in a light petroleum distillate with furfural having water dissolved therein in an amount ranging from above 1% to saturation at atmospheric temperature, separating the f urfural phase from the petroleum distillate phase containing purified rosin, and recovering from the two phases the resinous components dissolved therein. 7

2. The method of refining a resinyl material selected from the group consisting of rosins, rosin acids, rosin esters, rosin alcohols, and esters of rosin alcohols which comprises treating about a 10% to about a 40% by weight solution of said material in a light petroleum distillate with furfural in an amount ranging from about to about 150% by weight based on the weight of rosinyl material in said solution, said furfural having water dissolved therein in an amount ranging from above 1% to saturation at atmosphe'ric temperature, separating the -furfural phase from the'pet roleum distillate phase contaming-purified rosin, and recovering from the two phases the resinous components dissolved therein.-

'The'method of refininga rosinyl material selected from the group consisting of resins,

Use of furfural V rosin acids, rosin esters, rosinalcohols, and'esters of rosin alcohols which comprises treating about a 10% to about 1a-40% by weight solution of said materialin alight petroleum distillate with iurfural in an amount ranging from about 50% to about by weight based o-nrthe weight of .rosinyl material insaid solutiorn'said furfural having water dissolved therein in an amount ranging from above 1% to saturationat atmospheric temperature,- maintaining the mixture at an elevated temperature sufiicient to render it homogeneous, and then s'eparatingthe fu'r'fural phase from the petroleum distillate phase containing purified rosin, and recovering from the two phases the resinous components dissolved therein.

4. The method of refining a rosinylmaterial selected from the group consisting of resins, rosin acids, rosin esters, rosin alcohols, and esters of-rcsin alcohols which comprises treating about a 107% to about a-40% by weight solution of saidmaterial in a light petroleum distillate with furiural an amount ranging from about 0% to about 159% by Weight based on the weight'o'f rosinyl material in said solution, said iuriural having Water dissolved therein in an amount ranging from above 1% to saturation at atmospheric temperature,maintaining the mixture-at an elevated temperature sufficient to render it homogeneous, cooling the mixture at least to 25 and then separating thefurfural phase from the petroleum distillate phase containing purified rosin, and recovering from the'two, phases the resinouscomponents dissolved-therein.- V

5. The method of refining rosin which comprises contacting about a 10% to about a 40% by weight solution thereof in gasoline with furiural in an amount ranging from about 50%to about 150%; by weight based on the weight of rosinin said solutiomsaid furfuralrhaving water dissolved therein in an amount ranging from about 1% tosaturation atatrnospherictemporature, maintaining the mixture at an elevated temperature sufficient to render it homogeneous,

' coolingthe mixture at 1Q3,St' 'tO 251 F., separating the gasoline and furfur-al phases, and-recovering the rosin dissolved in saidphases.

6. The method or refining a rosin ester which comprises treating about a. 10% toabout a 40% by weight solution thereof in gasoline with furfural inanamount ranging irom about 50% to about 150% by weight based on the weight of rosin; ester in said solutionsaid furiural having water dissolved therein inan" amount ranging from above 1% to saturation at atmospheric temperature, maintaining the mixture at an elevated temperature sufficient to render it homogeneous, cooling the mixture at least to 25 F.-, separating the gasoline and furiural phases and recovering the rosin ester dissolved-insaicl phases;

'7. The method of refining a total aromatic extract of pine wood which comprises contacting about a 10% to about a 40% by weight, solution thereof in gasoline with iurfural in an amount ranging from about 50% to about 150% by weight based on the weight of extract in said solution, said furiural having water dissolved therein in an amount ranging from above 1% to saturation at atmospheric temperature, and then separating the gasoline and iurfural phases, and recovering the rosin dissolved in said gasoline phase.

DONALD A. LISTER. 

